Slider for heat assisted magnetic recording including a photo detector for monitoring laser power

Abstract

An apparatus includes a slider including an air bearing surface and a waveguide configured to receive light from a light source, a sensor positioned to receive a portion of light emitted by the light source prior to the light exiting the slider at the air bearing surface, and a controller controlling the light source power in response to a characteristic of the sensor.

1. An apparatus comprising:
 a slider comprising:
 an air bearing surface; and 
 a waveguide configured to receive light from a light source and emit the light from the slider at the air bearing surface; 
 
 a sensor formed on the waveguide to receive a portion of the light leaked directly from the waveguide prior to the light exiting the slider at the air bearing surface; 
 wherein the sensor is formed on a continuous portion of the waveguide, the continuous portion of the waveguide extending at least from the position of the sensor to where light is emitted from the slider at the air bearing surface during use; and 
 a controller to adjust power of the light source in response to a characteristic of the portion of the light received by the sensor. 
 
     
     
       2. The apparatus of  claim 1 , wherein the sensor is positioned to receive light that leaks out of the waveguide. 
     
     
       3. The apparatus of  claim 1 , further comprising:
 a splitter positioned to direct the portion of light to the sensor. 
 
     
     
       4. The apparatus of  claim 1 , wherein the waveguide includes a bend, and the sensor is positioned adjacent to the bend. 
     
     
       5. The apparatus of  claim 1 , wherein the sensor comprises:
 a photovoltaic cell or a photoconductive element. 
 
     
     
       6. The apparatus of  claim 1 , further comprising:
 a solid immersion mirror configured to receive light from the light source, wherein the sensor is positioned adjacent to or in the solid immersion mirror. 
 
     
     
       7. The apparatus of  claim 1 , wherein the sensor detects light reflected from the air bearing surface. 
     
     
       8. The apparatus of  claim 1 , further comprising:
 a solid immersion mirror configured to receive light from the light source, wherein the sensor is positioned to detect a portion of the light in a central portion of the solid immersion mirror. 
 
     
     
       9. The apparatus of  claim 1 , wherein the characteristic of the sensor comprises one or more of: resistance, current and voltage. 
     
     
       10. The apparatus of  claim 9 , further comprising:
 a memory for storing the resistance, current or voltage. 
 
     
     
       11. The apparatus of  claim 1 , wherein the sensor comprises:
 a photovoltaic element or a photoconductive element. 
 
     
     
       12. The apparatus of  claim 1 , wherein the sensor is bonded to a surface of the waveguide. 
     
     
       13. The apparatus of  claim 1 , wherein the sensor is fabricated to detect light leaking from a bend in the waveguide. 
     
     
       14. The apparatus of  claim 1 , further comprising a collimator is constructed to reflect the portion of the light to the sensor. 
     
     
       15. The apparatus of  claim 1 , further comprising a grating to direct the portion of the light to the sensor. 
     
     
       16. A method comprising:
 producing a light from a light source; 
 directing the light to a waveguide in a slider; 
 producing a signal representative of a portion of the light leaking from the waveguide directly onto a sensor formed on the waveguide prior to the light exiting an air bearing surface of the slider via the waveguide, wherein the sensor is formed on a continuous portion of the waveguide, the continuous portion of the waveguide extending at least from the position of the sensor to where light is emitted from the slider at the air bearing surface during use; and 
 controlling the light source power in response to the signal. 
 
     
     
       17. The method of  claim 16 , wherein the portion of the light leaks out of a bend in the waveguide. 
     
     
       18. The method of  claim 16 , further comprising:
 using a magnetic sensor to measure recording quality of recorded information on a storage disc; and 
 controlling the light source power to optimize the recording quality. 
 
     
     
       19. The method of  claim 16 , wherein the light source power is reduced in a non-writing condition. 
     
     
       20. The method of  claim 16 , further comprising:
 monitoring light source aging. 
 
     
     
       21. An apparatus comprising:
 a slider comprising:
 a laser; 
 a waveguide configured to receive light from the laser and to emit the light at an air bearing surface of the slider; 
 a photosensor formed on the waveguide to receive a portion of light directly leaked from the waveguide, wherein the photosensor is formed on a continuous portion of the waveguide, the continuous portion of the waveguide extending at least from the position of the photosensor to where light is emitted from the slider at the air bearing surface during use; and 
 a magnetic sensor; and 
 
 the apparatus further comprising a controller to adjust output of the laser in response to a magnetic readback signal from the magnetic sensor and a characteristic of the portion of the light leaked directly from the waveguide and received by the photosensor. 
 
     
     
       22. The apparatus of  claim 21 , wherein the photosensor detects light reflected from a storage medium.